The invention pertains to a device for operating a clutch, especially an automotive clutch, with a clutch lever pivoted on a pedal mount or on a similar stationary support part, which clutch lever has two end positions, one of which corresponds to the engaged state of the clutch, while the other corresponds to the disengaged state of the clutch, with a past-dead-center spring or overcenter spring that acts on the clutch lever, which spring exerts a force on the clutch lever when the clutch lever is positioned between the dead-center position and an end position, such that the force is directed towards this end position, and with additional spring mechanisms, which act on the clutch lever to reduce the pedal force that must be applied to it between the end position corresponding to the engaged state of the clutch and the dead-center position.
Systems for reducing the pedal force during the clutch disengagement process are well known and are used by many car manufacturers. The basic problem here is to reduce to a reasonable level the amount of pedal force that must be applied to the clutch lever during clutch disengagement, since the necessary force is quite large due to the necessarily high contact pressure of clutches for modern high-powered engines. This problem is solved with the use of a past-dead-center spring that acts on the clutch lever.
However, the advantage obtained with the past-dead-center spring in the prior art, namely, pedal force reduction between the dead center and the disengagement end position of the clutch lever, is accompanied by the disadvantage of an undesirable increase in the pedal force that must be applied at the beginning of the clutch lever travel path, i.e., from the engagement end position of the clutch lever to the dead-center position.
German patent DE-PS 36 36 748 describes a device of the type known in the art. The purpose of this device is to achieve a low pedal force over the entire travel distance of the clutch lever and thus to improve driver comfort. In this device, a compensating spring that acts continuously on the clutch lever is used as the additional spring mechanism. This has the disadvantage that the force of the compensating spring acting on the clutch lever is added to the force of the past-dead-center spring after the dead-center position has been reached and until the clutch lever arrives in its disengagement end position. To reduce this undesirable effect, DE-PS 36 36 748 proposes expensive measures, which, to put it simply, are based on suitable dimensioning and/or lever action of the compensating spring. However, the undesired addition of spring forces along the segment of the clutch lever travel path between dead center and the disengagement end position cannot be entirely eliminated.